01 -
Let the onions slowly cook in melted butter over medium heat for 5 minutes with a lid on, then lower the heat, stirring now and then for half an hour, or until they're deeply golden. Finish with vinegar to scrape up the tasty bits.
02 -
Divide the beef into three and shape into patties. Don't season them too soon; wait until right before cooking. Get the griddle to a hot 375–400°F.
03 -
Sear the patties in avocado oil for about 3 minutes per side until browned.
04 -
Spread butter on each side of the rye bread slices. Pop them on the hot griddle and toasty them up for 1 to 2 minutes on each side.
05 -
Stack the cheese, caramelized onions, and a burger patty on a piece of toasted bread. Cap it off with another slice and enjoy!